


Showing the Ropes

by AngeliaDark



Category: Undertale (Video Game)
Genre: Alternate Universe - Swapfell, Alternate Universe - Underswap, BDSM elements, Fontcest, M/M, Multi, Undertail, Voyeurism
Language: English
Status: Completed
Published: 2017-04-22
Updated: 2017-05-06
Packaged: 2018-10-22 09:58:56
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 2
Words: 7,895
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/10694676
Author URL: https://archiveofourown.org/users/AngeliaDark/pseuds/AngeliaDark
Summary: Underswap Papyrus sees the relationship the Swapfell brothers have and begins getting ideas concerning his own brother.  The Swapfells decide to show him the ropes of just how good it can get.  Underswap and Swapfell clash of the universes!





	1. Chapter 1

A commission piece for sapphire-sphinx on tumblr!  If you're interested in commissioning me, check out my [Commission Page](http://angelia-dark.tumblr.com/post/158295452224/opening-up-writing-commissions) and hit me up with a note or chat!  Also accepting [Coffees](https://ko-fi.com/A785GD2)!

* * *

 

 

Quite frankly, with all the different possibilities and weird shit that Stretch had seen in timeline after timeline, cross-universal shenanigans concerning different versions of his universe—and of himself and his brother—was almost EXPECTED by the time it actually happened.

There were MULTITUDES of universes, too many to even contemplate counting, but one seemed to have a mutual interest in his own, and ironically, it was very similar to his own. And...very different.

Not different enough to be unique in having built machines intended for interaction with other universes, though, as seen when other versions of himself and his brother arrived through his machine one day with no warning.

The brothers that he saw face-to-face were physically identical to him, and even had similar airs of being, but five minutes with them showed just how different things really were.

His other self—'Slim', he'd been dubbed—was very much like himself; laxed, chill, and didn't seem to put in much effort for much of anything that wasn't necessary. His physical appearance wasn't too far off, save for a large maxilla crack on the left-hand side of his face and a sharp golden tooth to go with it, his other sharpened to match. Like Stretch, he had a seemingly endless supply of cigarettes that he was almost constantly smoking.

The Sans on the other hand...

While Stretch's own brother had been nicknamed 'Blueberry' for how sweet he was and his proficiency in Blue magic, Stretch immediately coined this guy as 'Blackberry'; dark, rich, and tart. At first glance his attire seemed similar to Blue's, but a secondary look showed Stretch how risque it really was; an official-looking breastplate was the only professional piece on this Skeleton, the rest decked out in leather shorts, boots, and gloves, the ensemble completed with a red bandanna juxtaposed to his own brother's blue one.

The most glaring difference was that this Sans had a large crack over the left eye socket and a jaw full of sharpened teeth.

Stretch's own Sans was all organic curve and smoothness, but there was nothing smooth about this Sans other than the way he moved. After the initial realization that they were just different versions of the brothers, Stretch could hardly say they were the same Monsters.

The other Skeletons didn't seem bothered by the strangeness of this world and made themselves right at home after being invited by an enthusiastic Blue, who began asking questions at a mile a minute and hardly giving his other self time to answer. During this time, Stretch couldn't help but notice that Slim hardly spoke to answer, and instead seemed amused by it all and content with observing rather than participating.

Come to think of it, Slim didn't do much of ANYTHING, at least not without Black's orders. Not suggestions or directions— _orders_.

At first, Stretch thought that Slim's collar was a fashion statement but the more interaction he saw with the other brothers, the more he became convinced that it was not the case. Black seemed to be an absolute domineering force from his tone to his movements, speaking in a way that demanded nothing but obligation and obedience, something that Slim was all too eager and willing to obey.

A little too eager.

Sometimes Stretch would see his doppelganger almost kowtow to his brother with the oddest sort of devotion that bordered on worship. Not that Stretch didn't spoil and adore his own brother, goodness no...but the downright SERVITUDE that Slim displayed was a little off-putting, especially since Black seemed to be comfortable with it—EXPECT it, even. Like a little prince being pampered by his servant.

He couldn't help but pay closer attention to the other brothers, trying to piece together the niggling suspicions in the back of his mind, and found that his suspicions weren't entirely unfounded. Just small subtleties—the closeness Black and Slim had with one another, the lingering affectionate touches, and walking into the basement and finding Slim bent over the worktable while Black had him pinned while pulling a chain attached to Slim's collar with enough force to nearly asphyxiate him.

Not exactly a reassuring sight for his suspicions, nor was it something he could get out of his mind no matter how hard he tried. It was the last thing he had wanted to see, and not just because of the obvious reason of it being that they were brothers.

It had served to only exacerbate his own conflicted feelings toward his own brother.

Stretch kept his distance for some time from the other brothers for some time, trying to wrap his head around it. He supposed it shouldn't be THAT surprising; considering the multiverse, it was definitely plausible that in at least ONE he and his brother would be lovers. But the fact that he already had those feelings seemed frighteningly justified by the sight of his and his brother's doppelgangers rutting in the basement.

It was unavoidable that he'd have to face them again, and he could FEEL the flush of embarrassment crawl over his cheekbones in their presence, able to now plainly see the gestures between them. Black's languid, lingering touches on Slim's bones, Slim's heeling adoration in his eyelights, practically salivating when Black would lean over or stretch out with—as he now observed—deliberate visual appeal.

He could only keep his eyelights averted and his head down as the other brothers walked in for breakfast, Black grousing at Slim to do laundry more often while Slim only smiled and nodded in appeasement.

Blue hummed to himself as he set to the refrigerator, shooing Black away to the table. “You're still guests!” he said as he fished out eggs and bacon to make breakfast tacos for the sixth morning in a row and set out to cooking. Black huffed but sat at the table.

“Fine,” the darker Sans replied before turning to Slim. “Coffee.”

Slim nodded and stood up, silently fetching coffee from the carafe that Stretch already had going and putting in exactly three spoonfuls of sugar and a large splash of milk before handing it over to his brother. Black sipped it, deftly reaching up and petting his brother's head and taking no note as the taller brother almost purred with happiness.

While Blue was busy cooking during this exchange, Stretch could only watch, feeling his cheekbones warm at the further implications this brought him, getting an idea of what his relationship REALLY entailed and starting to have some different thoughts about it. The collar, the roughness, the commands...it seemed very...dominating. Almost like they weren't brothers, but rather a master and his servant.

It was a sobering thought, Stretch mused. What sort of basis of relationship did that even give? And was it even healthy? Slim SEEMED happy enough with it, but Black barely smiled at his brother and hardly ever spoke with anything other than a sharp, commanding tone. In retrospect, Slim seemed to behave more like a Dog Beast under Alphys's command than a Skeleton proper, and that...

...it was odd. It was odd, and Stretch didn't know what to make of it.

After the initial interest played out its novelty, Stretch took a moment to wonder if it was entirely in good standing. The juxtaposition between the other brothers suggested a literal master and servant relationship between the pair and as far as being brothers went, it was more than odd for Stretch to think about. Rather, it was worrisome.

Stretch was under no delusion of the strength that Sans—ANY given Sans—had in the multiverse; it would take little effort for one with lesser scruples to garner control over someone. He'd seen the absolute force of terror of someone with that conviction taking control in the Fell universe, who was to say it couldn't happen again, but a Sans doing the controlling?

As much as he had been avoiding them for the past couple days, he then turned and began paying closer attention, feeling a need to right any wrongs that there might be. As much as he felt a soft spot for Sans—any Sans—he wouldn't stand for one being cruel and sexually abusive.

He instead saw casual closeness between them that would meld into more intimate gestures from time to time, mostly when they thought no one was watching. Most of it, Stretch noticed, was initiated by Slim. His doppelganger was always hovering close, holding hands, and on more than one occasion rested his skull against Black's shoulder or femur when they were alone.

Slim didn't SEEM to be in any distress, but Stretch wasn't 100% convinced. Black just seemed too....harsh to be fully trusted, in Stretch's opinion. That paired with the fact that Slim seemed a few wicks short of a full candelabra only exacerbated his suspicions.

Still, it didn't help that he kept thinking back to what he had seen in the basement, and whenever he thought about THAT, he kept seeing his own brother in that scenario. So proud, so controlled, keeping composed the whole time he was pounding him into the—

No, no no no no no, not HIM, it was Black and Slim.

Oh boy.

This wasn't good.

Great. Now he couldn't even look at his own brother without having even WORSE thoughts concerning him.

Stretch stepped out of the house and made his way to his sentry station/burger stand and fished out a spare pack of cigarettes, having been too distracted to keep up with his stash back home. He lit one up and exhaled the smoke, slumping against the post.

This was getting ridiculous, he thought to himself. He shouldn't be feeling this way, fantasizing about his brother like that, getting hot under the collar just from seeing his brother in remotely the same vicinity as Black, as similar as they looked. It REALLY didn't help that Blue liked to play with Black's equipment out of curiosity, making Stretch wonder how his brother would fare learning how to USE them.

…....NOT HELPING.

He dropped his head back on the post, closing his eye sockets and taking another drag of his cigarette, trying to force those images and fantasies out of his head.

“You got another one of those?”

Stretch sat up straight, looking over and seeing Slim standing close by, hands in his pockets and eyeing the cigarette between Stretch's teeth. Stretch blushed a little before nodding and slipping the pack out of his hoodie pocket and holding it out. Slim fished one and flicked open his own lighter to light it up. “Thanks,” he replied, joining Stretch in leaning against the post as he focused on his smoke.

Stretch stood there quietly, not knowing what to say. This was the first time he'd been alone with his doppelganger since the other pair came to his universe, and it was incredibly awkward. He gave Slim a side-glance, getting an eyeful without the smaller counterpart to compliment him.

Without Black next to him, Slim was still lax and casual, with half-lidded eye sockets and a lazy hint of a smile. Other than the maxilla crack and gold fang, Stretch would've thought he was looking in the mirror, save for the fact that the relaxed demeanor was genuine.

It was a little envy-inducing. Stretch normally felt stressed 24/7 while putting forth a chill front, but it was better than working himself up. Fake it 'til you make it, right?

Slim's eyelights flicked over to lock with Stretch's, his smile widening. “See somethin' you like, buddy?” he asked, a golden-orange tongue slithering out from between his teeth to flick the end of his cigarette suggestively. Stretch's cheekbones flared hot, averting his eyelights as Slim chuckled. “Can't blame ya....I AM a piece of work, hm?”

“Funny,” Stretch muttered, finishing off his cigarette. “....so what're you doin' out here?”

Slim grinned, exhaling smoke through his teeth. “No smokes in the house,” he replied, holding up the cigarette. “I knew you'd be holding.” He stuck it back between his teeth, slipping his hands into his pockets. “What're YOU doin' out here, though?”

Stretch gave a one-shouldered shrug, keeping his gaze away. “Just having a smoke,” he replied. “Nothin' wrong with that.”

“.......all the way out here?” Slim queried, sounding almost amused. Stretch's cheekbones went hot, and it didn't go unnoticed by his doppelganger. Slim exhaled smoke through his nasal passage, his smile turning sly. “...embarrassed of me an' my brother? Or...maybe JEALOUS?”

Stretch nearly spat his spent cigarette out from between his teeth, his entire skull orange. “E-exCUSE me?!” he stammered. “What the hell is that even supposed to—“

“Don't be thick, I know you know about us,” Slim said, leaning back against the post. “It's not like we're completely subtle.” He closed his eye sockets. “I don't blame you for bein' a little wary about it. Not every universe is like ours, and not everyone gets our relationship.” He took the cigarette out from his teeth and tapped the ashes off the end. “So which is it? Embarrassed, or jealous?”

Stretch stammered, unable to coherently answer for several moments. “I'm—that isn't—I'm not—“

“Chill out buddy, it's cool,” Slim interjected, rolling his eyelights. “It's not for everyone, I get it. Just asking so we'll know when to put a sock on the door, or if we should leave it cracked for your voyeuristic kicks.” He gave Stretch a serious look. “I'm not gonna judge you, man, considering what I like to get off.”

Stretch was silent, though the orange of his face darkened guiltily. Slim noticed, nodding. “Figured,” he said. “Look, if you wanna watch, go ahead an' watch, though I'd talk to m'Lord about it first.”

“......your what?”

Slim smiled, his eyelights having a mischievous gleam. “Oh yes,” he chirped. “He's my Lord, and I am his humble servant, dedicated entirely to him, mind, body, and soul.” He smirked, trailing a finger down his front to trail over his belt buckle. “I do ANYTHING for him....and I do mean ANYTHING.” His eyelights glimmered at the stunned expression on Stretch's face. “Wouldn't YOU do anything for YOUR brother?”

He laughed, grinding out the rest of his cigarette into the pole. “That is, IF you're into that sort of thing,” he continued. “Let alone have those feelings for your brother. Like I said, not every universe is like ours. Not even those in our universe completely understand what me and m'Lord have.” He grinned, tugging on the D-ring of his collar. “You think this is for decoration?”

Stretch rubbed his hot cheekbone, averting his eyelights again. “....and....that leash....?” he asked delicately. Slim blinked, then laughed again.

“Oh, you saw that?” he said, crossing his arms. “I like having my cervicals choked, no big deal. That was VANILLA compared to what we usually do.” He eyed Stretch's reaction critically. “It's all consensual, I can assure you, if that's what you're worried about. We've been involved in this lifestyle for a long time, and we've gotten to a point where we know our limits through trial and error.” He smiled almost wickedly. “I'm a masochist in every sense of the word, albeit a learned one. It's all about experimentation, my friend.”

Stretch stared. “....experimentation?”

“Oh yeah, and plenty of it.” Slim stretched, grinning. “Choking, bondage, cutting, burning, bone-breaking and mending....I'm fond of whips and m'Lord likes edging and sadism. He was the one who introduced us to our lifestyle, and he takes so much care of me even outside the bedroom.” He gave Stretch a sly look.

“I'm sure if you wanted some pointers, m'Lord would be happy to oblige...”

“NO!” Stretch yelped, holding his hands up. “Uh......no, that's....that's fine, I'm.....” He stared at the ground, his cheekbones glowing bright orange. Slim smirked, nudging his shoulder.

“You prefer your own brother, hm?” he teased. “Understandable. Nothing quite like the original. But it's your business if you wanna try anything, not mine.” He gave Stretch a once-over. “But...I can tell you're a sub. You'd be happy being the receiver, most definitely.”

Stretch's skull was in danger of catching on fire. “Wow,” he said. “Okay. Yeah. I need, like....half Muffet's top shelf right now. And more cigarettes. So much more.” He turned and tugged his hood up, hurrying away from the scene of his shame.

Slim stared after him, shrugging before turning to leave back for the house when he was grabbed and turned around, his lapels clasped tightly in Stretch's hands.

“Do NOT tell my brother about this!” Stretch hissed desperately. “PROMISE me you won't tell him!”

Slim blinked slowly, reaching up and delicately removing Stretch's hands from his jacket. “I promise I will not tell your brother,” he replied back, his expression serious. “Promise.”

Stretch nodded and turned to hurry off to Muffet's, looking like he was trying to NOT look like he was running...and failing miserably. Slim watched him leave, then rolled his shoulders and trekked back to the house, kicking snow off of his shoes as he stepped inside.

Black was sitting on the couch, flipping through the television and looking unamused with what was offered. “And where were you?” he asked without looking away from the screen.

“I was with Stretch,” Slim replied. Black made a sound of half-interest.

“And where is he NOW?” he demanded. Slim remained silent for a moment before walking over and kneeling in front of him, his head lowered but his eyes glimmering with mirth. “...Papyrus?”

“...there is something I would like to tell you, m'Lord,” Slim said, his grin widening. “Something I think will interest you very much.”

 


	2. Chapter 2

**Notes for the Chapter:**

> GotDANG this went longer than I thought. O_O

Stretch spent more than his fair amount of time at Muffet's knocking back three stiff drinks on top of his usual honey and generally procrastinating going home.

He knew he had to at some point; if not, Blue would stalk in here in a huff and be in a sour mood for the rest of the evening, especially since they both had guests to entertain. It would be especially bad considering he was half-drunk and already edging on his tab limit with Muffet.

If there was one thing he couldn't handle right now, it was his brother stalking in to manhandle him back home. He didn't want to be near Blue unless entirely necessary for awhile, until he was able to stuff those feelings back into the box of Bullshit Emotions from whence they came, and hopefully have the other brothers back in their own universe before something could pick that lock again.

Finally, with all the self-control he could muster from this hell of an evening, he cut himself off, paid into his tab of what he had in his pockets (13 G), and trudged his way home, hoping he could sleep this experience off with his hangover.

His hands deftly went to his pockets by reflex for a pre-sleep cigarette, and he felt a twinge of annoyance when the pack he felt was empty. _'Bastard took my last one,'_ he thought bitterly, letting out a gruff sigh as he walked up to his house and let himself in.

Had he not been half-drunk and emotionally drained, he would have noticed right away that every light in the house was off; however, his lack of immediate acknowledgment left him open and vulnerable to what happened next. In an instant, there were strong arms curled around his head and cervical bones in a sleeper hold, tugging with a sudden tightness and a low, husky voice right by his head said

“Count to six.”

And like an idiot, Stretch's immediate first thought was _'One...two...'_

And then darkness.

* * *

 

Stretch's skull was pounding when he came to and his cervicals were stiff. He groaned, turning his head to the side to flex it out and made a move to rub at it when he found both his hands were restrained.

Awareness slammed into him, realizing now that he was restrained with his hands above his head, his hoodie and shoes gone, and a cloth covering his eye sockets. None of those things did anything good for reassurance.

Stretch tugged on the restraints to test their give and found none, somehow finding the common sense to know that calling out would just alert his assailants as he tried to shift the cloth from his eye sockets with no success. Shit, if only he could focus enough to teleport out of here...he didn't trust himself hungover and restrained, though. Knowing his luck, he'd teleport out and leave his bound arms behind, and gods KNEW what that would do to his shoddy HP.

A muted sound to his left made him freeze, straining his hearing to pick it up again, and recognized the sound of someone shuffling outside a closed door. He held his breath and remained still, feeling anticipation crawl cold up his spine as the door opened and slow, heavy footfalls approached.

“...you don't have to pretend to be out,” came the voice of...well, himself. Slim, then. “I know you're awake.”

Stretch flexed his hands, turning in the direction of Slim's voice. “What's going on?” he demanded, not bothering to feign unconsciousness. “Did you do this?”

“Sort of,” Slim replied, and Stretch could almost HEAR the shrug that no doubt accompanied the answer. “I knocked you out harmlessly and carried you here. But I didn't do the restraining. I'm no good at knots.”

“Sucks to be you,” Stretch grumbled, unamused. “What the hell's going on?! Why am I tied up and blindfolded?”

He heard Slim step closer. “You'll see,” his doppelganger replied. “But for now, you need to remain calm. Will you be calm? I'll take off the blindfold if you're compliant.”

As much as Stretch wanted to throw a bitch of a fit at the situation, he wanted answers, and he wanted out of these restraints. So he gave a curt nod. “Use your words,” Slim said, and Stretch growled, the restraints creaking slightly at the tug he gave in ire.

“Yes,” Stretch hissed. “I'm calm. So fucking calm.” He heard Slim make a soft sound of amusement, then felt phalanges slide under the cloth and tug it loose to remove it.

Stretch took a moment for his eyesight to adjust, though it didn't take much; he was in his own bedroom with the lights off and candles dimly illuminating the room. His mattress was shifted off to the side, and he found that he was lying reclined back on some sort of padded slab, his arms tied neatly over his head and loose ties around his ankles.

He shuddered at the implications of what exactly this could entail, turning to Slim for explanation and felt his voice halt behind his teeth. Slim's clothing was mostly gone with only his pants remaining, his scarred, chipped, and cracked frame on full display. He had a pair of thick black leather shackles around his wrists and a tag attached to his collar with an ornate **S** emblazoned on the gleaming metal.

Stretch shifted uncomfortably on the slab. “What's going on?” he repeated, fighting to keep his voice calm as promised. Slim smiled, his gold tooth glinting in the candlelight.

“Don't worry,” he said. “You're perfectly safe. We just needed you to not cower out.”

“....'we'?”

“A bit slow on the uptake, isn't he?”

Stretch jolted at hearing a third voice, his eyelights scanning the room before landing on Black, who was seated in the corner back in shadows. He felt a shudder creep up his spine; how the hell had he not sensed him in the room!?

“M'Lord is very good at being undetected,” Slim provided as though sensing Stretch's question. His voice carried a quiver of excitement. “It's especially thrilling during solitary edging. Sometimes he's there, and sometimes he isn't. I never truly know.”

“You can stop sucking my dick, you thirsty mutt,” Black scoffed. “This isn't about you and you know it.”

Slim ducked his head, though his eyelights gleamed mischievously. “Is it not your dick I should be sucking then, m'Lord?” he purred, walking his fingertips over the slab playfully toward Stretch's hip. Stretch shifted his pelvis away, the spike of horror he felt being overwhelmed by a brief shock of Black cracking a riding crop loudly against the wall.

“He is NOT yours to touch, you degenerate beast!” Black snapped, standing up and crossing the room in three elegant strides. “Heel, you mutt, and stop embarrassing yourself!”

Slim dropped to his knees, his head lowered as he went silent. Black gave him a look of annoyance before turning his attention to Stretch, his eyelights glimmering a sharp electric blue as he eyed Stretch over.

Stretch felt himself squirming under the smaller Skeleton's scrutiny, feeling as though Black could—heh—see right through him, down to the soul. The thoughts in his mind weren't exactly pure to be seen by anyone, let alone a Sans that so very much resembled his own brother, and one dressed so provocatively.

Black had foregone the armored pieces, and was now only wearing a pair of black thigh-high stockings, matching black gloves that came halfway up his humeri, and shorts with only his red bandanna serving as a top. He had the riding crop bent between his hands, their tight grip in contrast with the effortless ease the rest of himself was poised. “It's come to my attention that you've been suffering,” Black said, tapping the end of the crop into his palm. “And it's a real shame, considering.”

“.......considering?”

“Considering how obviously in love you are with your brother.”

Stretch froze, his frame trembling in a cold sweat. “Wha....I......I'm not.....” he stammered before turning to Slim, whose head was tilted slightly to give Stretch a view of a knowing smirk. “YOU TOLD HIM!?” Stretch tugged on his restraints, feeling his eye sockets dampen with shame and betrayal. “YOU BASTARD! YOU PROMISED—!”

“I promised I would not tell your brother,” Slim said, his grin widening. “M'Lord is NOT your brother.” His shoulders shook softly with the barely-concealed laughter at the expression Stretch was giving him. “Don't hate the player, hate the game.”

“Enough, mutt,” Black said curtly. “Yes, he told me. And I am glad he did. This little dance of avoidance you have? Unacceptable.” He folded his hands behind his back, his eyelights sharp as he stared down at Stretch. “It's obvious you're no different than my own brother, unable to properly function without a firm hand guiding you along. Well, that's going to change.”

Stretch tensed in his restraints. “What the hell are you talking about?” he demanded. “You're not fuckin' doin' this to me—!”

“That's not up to you, newbie,” Black cut in, turning on heel and gliding back to his chair in the corner of the room. “And in any case, it's not up to ME, either. It's up to your handler.”

“My WHAT?”

As if answering him, the bedroom door opened and Stretch felt a flash of cold run up his spine when he heard the telltale sound of his brother's boots on the wood floor. Oh no, no no no no no, he couldn't let his brother see him this way, no no NO...!

“He's even more hopeless than I thought,” Black said from his place on the chair. Blue made a huffing sound, his hands planted on his hips.

“He's not HOPELESS, Black!” he retorted. “But yes...he HAS been repressing a LOT.” He walked over to Stretch, peering down at him with his baby blue eyelights that were glimmering with curiosity and a touch of indignation. “...you know, you could have TOLD me you felt that way toward me, instead of me having to hear it from Black. I thought we could tell each other ANYTHING.”

Stretch stammered, unable to find something to day to respond to that. “....what?” he finally managed, shifting in his restraints to see his brother better. “......Sans....I...do you even...know what you're saying?” He yelped when Blue gave his chest a smack.

“I'm not an ignorant little child, Papy!” he replied. “In case you've forgotten, I'M the older brother!” His expression softened. “And we agreed we'd be honest with each other. So...why would you keep this from me?”

Stretch shifted uncomfortably, aware that his skull was probably orange by now. “...I...bro, I just...”

Black huffed a sigh from the corner. “Honesty is the number one policy, Stretch,” he said. “Even if the truth is uncomfortable.” He turned to his own brother. “Have you had thoughts about this universe's Sans, mutt?”

“Yes,” Slim replied immediately. “He resembles you greatly and I admit interest in the idea of a green Lord relearning everything, breaking himself in with me.”

“Greedy beast,” Black groused, his attention shifting to Stretch. “See? His dedication to me does not mean his attention doesn't shift, and he admits that. Though I admit myself interested in seeing how this plays out.” He leaned back in the chair, arcing the crop in his hands.

“It's obvious that a traditional relationship wouldn't work for you two. Traditional isn't exactly an option for us in general. So we'll dive right in with this...honesty. And I will be overseeing it.”

“Overseeing wha—“ Stretch's question was cut off by Blue leaning down and pressing their teeth together.

Out of a million things Stretch had expected to happen today, his brother kissing him didn't even crack the top ten. He didn't even expect it to be GOOD, but Blue seemed to know what he was doing as he swiped an ectoplasmic tongue across Stretch's teeth, eliciting a shudder from the taller brother. Blue leaned back, his cheekbones flushed softly as his eyelights glimmered down at Stretch.

“Black told me everything his brother told him,” he said. “And you really should have told me sooner, Papy. As big brother, it's my job to take care of you. And since you feel the same way about me as I do about you, we can work our way up from there.”

Stretch could only stare and process what had been told—and done—to him as Blue fiddled with something next to the slab that shifted it upward in a diagonal position. “...bro, what're you doing?”

“Do you trust me, Papy?”

Blue's question gave him pause. Did he? It seemed like such a foolish question, he ALWAYS trusted his brother to do the best he could for him.

But did he trust him with THIS?

Blue stood by him patiently as he waited for Stretch's answer. There was no air of urgency or rush from him or from the other two Skeletons in the room, but Stretch didn't want to keep Blue waiting like that. The fact that his brother felt the same way as him already made up 90% of his mind. The other 10%...

“Yes or no questions are best for indecisive beasts like him,” Black piped up from the corner. Blue nodded in agreement, giving his brother a smile.

“Do you love me the way I love you, Papy?”

Stretch flexed his hands, his cheekbones flushing slightly. “...yes,” he said, since there were only two ways to answer.

“Do you consent to me touching you?”

“....yes.”

“Do you trust me?”

“........yes.”

Blue beamed, clapping his hands together. “Oh, good!” he chirped, his eyelights going vaguely star-shaped. “Now, I know it can be a little awkward, but Black and Slim here know how to make this work. They won't steer us wrong with this, okay?” He pressed a kiss to Stretch's sternum. “I just want to take care of you. Will you let me?”

Stretch could feel his embarrassment reaching critical levels at the reminder that the other brothers were still here, but Black was sitting back neutrally and Slim was still kneeling on the floor, the glimmer in his visible eyelight almost jealous of Stretch's position. What was there to be jealous OF?

….....oh.

He exhaled heavily, leaning his skull back on the slab behind him. “......yes,” he said.

“Good,” Black said from the corner. “First and foremost, designate a safe word.”

Stretch frowned. “Why?”

“It's irresponsible to continue without one,” Black replied patiently. “If you are uncomfortable with anything, it can be said to stop what's going on, no questions asked. Questions come later to prevent a limit from being crossed in the future. Pick one.”

Stretch shifted in his restraints. “...'ketchup',” he finally said.

Black nodded. “Crude, but effective,” he said. “Nothing that can be accidentally blurted out. Now, according to my mutt, you also have the makings of a prime sub. Someone who wants to be spoiled and pleasured to ease the burdens of your everyday life, if only you allow yourself to give up control in complete trust. And who better than your strong, loving brother?” He glanced to Blue, who was looking almost excited. “He seems eager to take his part in that.”

“I really am, Papy,” Blue said earnestly. “And I DO want to take care of you. So please? Let me?”

Stretch weighed his options, feeling a calling in his soul that begged for relief of his burdens, his inclination toward laziness being utilized for something else entirely being an interesting prospect. But to submit himself completely to this the way Slim did?

Slim had SEEMED happy enough with his life, boastful even. Was it really that worth it?

“I'll....try,” he conceded. Blue beamed and Black nodded, pleased with the answer.

“Trying is the foundation for anything in this lifestyle,” he said. “Trial and error. Suffice to say, the similarities between you and your brother and myself and mine are many, but so are the differences. We can't expect you to enjoy everything we do, and considering your 1 HP status, you wouldn't be able to handle everything my mutt can.”

He leaned back in his chair, crossing his legs. “Nevertheless, I'm offering over my servant to aid in your experience. I'm sure you have many of the same pleasure points and he will know where they all are. Everything else is between you and your dom.”

Stretch felt his blush return full-force at the prospect of Slim being a participating member of this; he barely felt completely at ease masturbating, let alone having—literally—himself aid with it. Slim, on the other hand, apparently had no problem with this development, his eyelights gleaming almost hungrily with anticipation.

…...oh gods, was Slim actually _salivating_!?

“Papyrus,” Black said curtly, making Slim's spine straighten. “You are to only aid. You will not hinder Blue's work, nor will you overshadow it. You are a tool, not the hand that guides it. Am I clear?”

“Transparently,” Slim replied before shifting over to the slab, making quick work of undoing Stretch's cargo shorts.

Stretch didn't have time to properly protest before Blue was kissing him again, keeping a firm hand on his cheekbone to keep his head in place. Stretch shuddered, relaxing his jaw and allowing his magic to manifest itself into a tongue that slithered out to meet with his brother's.

Blue curled his tongue around Stretch's, a soft growl rattling at his frame before withdrawing his tongue, nuzzling Stretch affectionately. “You taste so sweet, Papy,” he said. “Almost as sweet as that honey you drink.” He pressed his teeth softly over Stretch's skull sweetly, keeping his hand firmly in place. “Just focus on me, okay? We only want you to feel good.”

Stretch craned his neck to lean into Blue's kisses, only deftly aware of Slim undressing him and running rough hands over his bones. He felt his frame twitch with every pass of the insides of his femurs, the outsides of his fibulae, and right behind his knees, cursing the knowledge that Slim knew just where his sensitive areas were.

Blue shifted attention to his neck bones, hands busied with stroking over Stretch's ribs and sternum while Slim began dragging his tongue over the sensitive joints between bones, the dual attention from both almost overwhelming Stretch already. Still, he tried to keep his attention on Blue as directed, focusing on the glistening smoothness of his brother's tongue, the spicy scent of musk and taco sauce, the strong pulse of Blue's soul and aura comforting over his own.

He was almost drunk on the sensations, and almost missed it when Black said, “Start off on the base level. Keep in mind his HP and your intents.”

Slim side-eyed his brother, his expression almost devious. “Of course, m'Lord,” he purred. “He is, after all, me. I know what he'll like.” He reached up and wrapped a hand around Stretch's spine, squeezing it hard as he scraped his teeth over the other's pubis.

Stretch let out a strangled gasp, his hips arching hard off the slab as his magic began churning and coalescing in his pelvis. Slim palmed at the magic, urging it to take form as Blue watched with intent interest.

“Scrape over his bones,” Black instructed. “Bite him gently, and then harder until he safe words.”

Slim barely had time to process that before he felt his brother bite his clavicle and scrape his phalanges over his sternum. The dull sting paired with Slim's ministrations of his magic melded into something WONDERFUL that had him feel like tensing his whole frame up and going slack at the same time, already feeling the starting build of an orgasm without his magic fully formed yet.

As though sensing this, Slim leaned in and curled his ectoplasmic tongue hard around the half-formed magic construct, pulling almost all of it into his mouth.

Stretch let out a strangled wail as his soul pulsed almost painfully, his soul and magic gushing residue. His body slumped on the slab, only his restraints keeping him upright. He rode out the rest of his orgasm, feeling his bones rattling from the aftershocks. After a few long moments, he became aware that both Slim and his brother had retreated to give him some breathing room. “...bro...?”

“I'm here, Papy,” Blue said, resting a grounding hand on Stretch's sternum. “Are you alright? Remember the safe word?”

Stretch nodded numbly. “...ketchup,” he answered, shifting in his restraints. “...I'm good...I'm fine...”

“Good,” Blue chirped, reaching down and undoing the restraints from Stretch's ankles. “Don't be afraid to say it, okay?” He kissed over Stretch's clavicles as he undid his pants, stroking at a thick tendril-like ectoplasmic appendage. His eyelights almost sparkled as he reached out with his free hand and brushed it over his brother's own magic before pressing his hips to Stretch's.

Stretch yelped, bucking hips hips hard, feeling his own magic flare and throb with desire that completely offset the revelation that he was going to finally be doing this with his brother. And he didn't even care if he had an audience, he WANTED this, he WANTED to submit himself to Blue, he just wanted his brother—

He shuddered hard when his brother's deep, breathy moans resonated against his rib cage where Blue's skull was pressed against. His bucked his hips faster to his brother's only to have his pelvis pinned down by Blue, who kept his movements slow and torturous. “Bro...Sansy, please...!”

“You're always so impatient,” Blue purred, the breathlessness betraying his authoritative tone. “But you're so sweet like this, brother...my big drink of honey...I could eat you up like this...!” He emphasized by biting one of Stretch's ribs sharply, drawing a gasp from Stretch.

Stretch bucked his hips as much as he could in his brother's grip, twitching and jerking every time Blue bit down and followed with a swipe over the bite with his tongue. He keened loudly, panting as he felt another orgasm build up. “S...Sans, please please please...!” he begged, jerking in the restraints. “I need it, I fuckin' NEED it...!”

“Language, Papy!” Blue chastised, grinding his hips harder. “If you want something from your big brother, you ask NICELY.” He bit down again, digging his fingers into Stretch's pelvis.

Stretch arched his hips hard, his head dropping back on the slab. “PLEASE—“ he wailed, tugging hard on the restraints. “PLEASE, Sans, please, I...!” He clenched his legs around Blue's hips, pulling him closer. “I need it I need you I—“ He cut off with a screech when Blue bit another rib, the sting of pain going straight to his groin as he came again, his legs locking tight around his brother.

It took longer to come down from this high, having still been sensitive from the last orgasm and still twitching and tingling over this one, that he didn't even notice Blue cumming right after. He became deftly aware of hands gently unclenching his legs from Blue's hips, and a prodding around his wrists.

Gentle hands on his cheekbones grounded him to the present, bringing his attention to bright blue eyelights. He was barely able to make out his brother saying, “Are you alright, Papy?”

Alright? He was fan-fucking-TASTIC. But he could only nod with a smile.

Blue smiled back, keeping a hold on Stretch as Slim undid the restraints and gently tugged him off of the slab and over to the waiting bed. Stretch relaxed in his brother's hold, reveling in the soft skull pets as he basked in the wondrous afterglow.

Behind him, Black stood up and walked over to Slim, who was on standby patiently. “We'll leave you two to hash out your details,” he said, hooking a finger through Slim's collar D-ring. “If you both agree, we'll continue. Call us if you need us, Blue.” He walked out of the room taking Slim along, shutting the door behind them.

Blue smiled, kissing Stretch's skull. “Feeling good still?” he asked. Stretch nodded, curling his arms around his brother.

“...yeah, 'm good,” he replied lazily. “...nice surprise there, though.”

Blue giggled. “I suppose it was,” he said. “I had words with Slim for how he got you to sleep. I told him to just wait until you crashed out on the couch.”

“Heh....yeah, it was weird,” Stretch said. “...so...you feel the same way...?”

“I sure do,” Blue chirped. “I'm a little disappointed I had to hear it from Black, but I'm glad you feel the same way I do.” He cuddled Stretch to him for several long moments. “...Black and Slim said they'd teach us how to have this relationship, if you're up to it. Naturally, not EVERYTHING they do, but...you know. Some things.”

Stretch felt his cheekbones blush, burying his face into Blue's shirt. “...about that...” he said, shifting a little. “...you seemed pretty...confident about what you were doing...”

Blue scoffed. “Oh honestly, Papy, it's not like I'm some ignorant virgin,” he said. “I AM your big brother, after all. I just don't like airing my own laundry to everyone in Snowdin.” He smiled, nuzzling Stretch's skull. “But it gave me enough experience to satisfy YOU. That's what's important. And if you're willing...we can do more of this.”

“....I guess those guys need something to do while we fix the machine,” Stretch said. “Other than defiling our kitchen table, anyway.”

“Oh, they won't do that again, I made sure of it.”

Stretch snorted, sitting up a little and rolling his shoulders to unkink his arms. “So...if we do this, am I gonna be calling you m'Lord?”

Blue nudged his arm. “NO, Papy, I'm totally not Lordish like Black,” he said. “You don't have to call me anything but Sans or Blue or bro.”

“But you ARE gonna be my dom, aren't you, Mister Future Guardsman Sir?”

Blue smiled, looking thoughtful. “...Sir....” he murmured. “That sounds nice. I like it.”

Stretch smiled too, feeling his soul flutter with anticipation. “...I'm not adverse to a little more of what we had earlier,” he said. “Not if you're not either.”

Blue beamed, clapping his hands. “Oh good!” he exclaimed. “Black! Slim! We're in!”

The other brothers walked in right away, having been waiting just outside the door. Black looked pleased as punch while Slim was nearly salivating at the sight of the newbies. “That's good to hear,” Black said, smiling with his razor sharp teeth. “We've covered the pleasure testing...and now we can try the punishment.”

Stretch's jaw twitched. “...Punishment?” he said. Black nodded, bending the crop in his hands.

“Of course,” he said. “You neglected to tell your dom about your feelings for so long, and caused so much unnecessary measures to make this happen. You need to be punished for such trouble.” He straightened the crop and handed it over to Blue. “Mutt, subdue.”

Slim strutted forward and knelt down in front of Stretch, taking the other's hands and tugging him to lay out on the bed face-down, keeping his hands in a vice grip around Stretch's wrists. Stretch shifted on the bed, his soul hammering in his rib cage as he wondered what exactly was going to happen.

Black put a hand on Blue's shoulder, guiding him behind Stretch. “The entirety of this part is intention,” he stated. “It will be different with you than it is with my pet, since my intention is to punish, but also to cause enough harm to take down a few HP. Mine is a tedious and dangerous HP edging play that you cannot trifle with, considering his handicap. However, with your intent in complete focus, you can give him the pain that pleasures him without harming his HP at all. As his dom, every action YOU make affects HIM. Be mindful at all times. Now...” He stepped back, sitting in the chair again. “Start off easy. Give him five lashings and a rest.”

Blue nodded, his hand gripping the crop as he turned to his brother. “Do you remember the safe word?” he asked.

Stretch nodded, his hands flexing rapidly. “...ketchup,” he said.

“Are you ready?”

Stretch nodded again. “Yes...Sir,” he added with a small extra surge of confidence. Behind him, Blue beamed and took a moment to focus himself before lashing the crop down hard on Stretch's sacrum.

Stretch jumped with a yelp, his pelvis arching back hard at the blow, feeling every other bone resonate with a tingle at the blow. Instinctively, he checked his own stats.

1 HP. Not so much as a dent to the decimals.

And his bones were STILL tingling.

Blue must have checked too because a second blow came, and a third, each one sending jolts of near-electricity through Stretch's whole frame, his HP never denting and the pleasure ebbing and flowing with the pain in waves, yelping and crying out after each blow, completely unused to such pain after all this time with his handicap.

“You're doing so well, honey!” Blue praised. “Only two more to go, and then we can rest with some hot cocoa.”

 _Only two more?_ he thought to himself as his bones twitched from the lingering sting and anticipation for more to come. His eyelights flicked up, catching Slim grinning down at him like he was the luckiest Monster in the Underground. And really, at this moment as he felt another lash come down, he really did feel like it.

 


End file.
